In a direct-injection spark-ignition internal combustion engine, a high injection pressure is required to atomize a spray of fuel. Accordingly, there is known a fuel supply device for pressure-feeding fuel in a fuel tank by a low-pressure side electromagnetic fuel pump (low-pressure pump), accumulating this low-pressure fuel in a common rail after highly pressurizing it by a high-pressure side mechanical fuel pump (high-pressure pump) and injecting the fuel into a combustion chamber by an injection pulse corresponding to a fuel pressure (fuel injection pressure) in the common rail. A feedback control is generally performed based on a detection value of a pressure sensor to keep the fuel injection pressure at a target injection pressure set according to an operating state of the internal combustion engine.
If the pressure sensor (high-pressure fuel pressure sensor) for detecting the fuel injection pressure does not indicate an accurate value due to disconnection or the like in the fuel supply device as described above, the fuel injection pressure cannot be accurately controlled.
Accordingly, in JP10-077892A issued in 1998 by the Japan Patent Office, a high-pressure pump is controlled to be in a maximum discharge amount state and a fuel injection pressure is estimated to be a maximum value in mechanism when a high-pressure fuel pressure sensor experiences disconnection or the like.